#include<iostream>
using namespace std;
#include<vector>
class Solution {
public:
    int countGoodStrings(int low, int high, int zero, int one) {
        vector<int> dp(high + 1, 0);
        dp[0] = 1;
        for (int i = 1; i <= high; ++i) {
            if (i - zero >= 0)
                dp[i] += dp[i - zero];
            if (i - one >= 0)
                dp[i] += dp[i - one];
            dp[i] %= 1000000007;
        }
        int ans = 0;
        for (int i = low; i <= high; ++i) {
            ans = (ans + dp[i]) % 1000000007;
        }
        return ans;
    }
};
int main() {
    Solution().countGoodStrings(3,3,1,1);
}